How do I defend against a horse fork?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
Block the horse's leg before the fork actually lands, if you can; if not, save the more valuable piece and accept the loss of the other. A horse fork can only happen if both target squares are genuinely reachable, so the earliest and cheapest defence is denying it a leg rather than reacting once it is already in place.
Prevention beats cure
Watch for an enemy horse heading toward a point where it would attack two of your pieces at once, and occupy one of its legs before it arrives. A single pawn or piece in the right spot removes the fork entirely, at far less cost than losing material to it later. See what makes a fork work in the first place for the mechanics behind why blocking a leg is enough.
If the fork has already landed
Save the more valuable piece, and check whether a counter-threat, especially a check, is available that is faster than the fork. If your own move forces a reply first, the opponent may not get to execute the fork at all.
Related questions
Can I ever ignore a fork?
Only if you have a check or an equal or greater threat that must be answered first.
Is blocking always possible?
No, sometimes the horse already has both legs clear by the time you notice. Then it is about damage limitation.
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